Two-stroke motor



'Feb. 8, 1949. H, ONVERT 1 2,461,199 I TWO-STROKE MOf IOR Filed July 18, 1945 9 lava e601 HEW/W 0011/1/51?)- pun/pa. Aframvsns Patented Feb. 8, 1949 OFFICE TWO-STROKE MOTOR Henri Convert, Lyon, France Application July 18, 1945, Serial No. 605,760

In France March 1, 1944 Section 1, Public Law 690, August a, 1946 Patent expires March 1, 1964 My invention relates to a two stroke motor the particular design of which bestows on it special properties chiefly from the standpoint of efliciency.

This motor is essentially characterized in that it comprises a differential double piston and cylinder group, the upper cylinder of small bore being used for feeding while the lower cylinder of higher bore provides the driving stroke, the common piston formed as a double cylinder being hollow and ensuring through its central channel the transfer under a pressure higher than normal, of the carburetted mixture into the lower cylinder providing the driving stroke.

Other features are associated with my novel assembly of two cylinders for furthering its operation. These features are chiefly as follows:

' (a) The rich gases are sucked into the part of smaller diameter of the upper cylinder, through a port uncovered at the end of its downward stroke by the corresponding head portion of the piston and are during the upward stroke of the piston urged back into an annular chamber in which they are submitted to a preliminary compression.

(b) The air required for forming the mixture enters the casing of the motor through peripheral ports uncovered at the end of the upward stroke by the skirt of the body portion of greater crosssection of the piston and are compressed during the downward movement.

The head portion of the piston comprises large openings opening into its central channel and ensuring on one hand at the end of the upward stroke the transfer into the casing of the rich gases which are then admixed with air and on the other hand at the end of the downward stroke the transfer into the cylinder providing the driving stroke of the air and gas mixture.

((1) The exhaust gases are removed through a number of ports distributed at the base of the periphery of the cylinder which allows reducing the height, said ports being uncovered at the end of the downward stroke by the upper part of the piston body.

The invention will be well understood by referring to appended diagrammatic drawing and to the complementary description relating thereto, said drawing and its description being obviously given only by way of an example and in no manner in a limitative manner.

In said drawings:

Figs. 1 and 2 are two views in elevational axial cross-sectionof the motor with the piston respectively at its higher and lower dead points.

6 Claims. (Cl. 123-73) Caf o 2. Fig. 3 is, at a larger scale, a horizontal crosssection through line 3-3 of Fig. 2. I

According to my invention, this motor comprises a piston constituted by two parts of different diameters: a head I and a body 2 moving inside a double cylinder comprising two corresponding bores respectively at 3 and at 4. This piston is connected in the usual manner with a connecting rod 5 pivotally secured to a crankshaft 6 rotating inside a fluid tight casing I.

This piston l-2 is tubular and is providedwith a central channel 8 communicating through its base with the casing while ports 9 provided at the periphery of the piston head I open into the upper end of the bore,

The cylinder 3 is provided at its lower end with a pipe [0 for the admission of rich gases and throughout its length with a lining I 2 showing at its upper part ports l3 which put thecylinder in communication with an annular chamber Hi.

The cylinderl inside which the carburetted mixture is ignited by means of the spark plug I5 is provided with ports 16 distributed throughout its periphery for the escape of the burnt gases opening into the exhaustcollector I1 on one hand and with portsl8 for the admission of fresh air into the casing 1 on the other hand.

Segments, respectively shown at l9 and 20, ensure the fluid-tightness of the pistons l, 2, in their cylinders 3 and 4.

The operation'of this motor is as follows:

First stroke The piston movingdownwards when the gases expand in thecylinder 4-, a reduced pressure prevails inside the cylinder3 above the piston head i while the gases inside the casing 1 are compressed.

Alittle before the end of the downward stroke, the lower piston 2 uncovers the exhaust ports l6 while the upper piston l uncovers above its segments IS the admission pipe H) for the admission of the rich gases coming from the carburettor, which allows the filling of the cylinder3. On the other hand, at this moment, the head or upper piston puts in communication through its transfer ports 9 the motor casing I with the upper Second stroke During the upward movement of the piston, the transfer ports 9 of the head I are closed at the samev time as the latter closes the opening contrary all the .modifications arrive in front of said ports i3, theserich gases are transferred into the casing I through the V 4 of the larger part of the cylinder, means for feeding a part of the combustible mixture into the outer end of the narrower part of the cylincentral channel 8 while the skirt of the piston 21 V uncovers the ports i8 so as to allow an admission of fresh air mixing with the rich gases.

A little before the higher dead point, the car buretant mixture compressed in the cylinder 4 isignited by the spark plug 45, and its explosion,

urges the system downwards so as to initiate-the driving stroke, at the same time as the piston is started again on its f rst stroke. The advantages provided by such a motor are easyto understand.

There is in fact an overfeed by reason of the very shape of the piston, the gases being admitted into the cylinder body at a pressure above theusual pressure;

The fresh gases which have only to pass through the piston wall, along passages the cross section of. which is much greater than is usual, arrive in a very short time inside the cylinder. I The cooling is considerably improved by the intense circulation of fresh gases inside the piston by reason. of the admission of the gaseous mixture, at the head of the driving cylinder.

The self ignition is thus prevented, which 7 allows the adoption of high compression rates.

On' the other hand, the direct admission or" rich gases is more unconstrained and more precise than in any extant motor, which leads to a reduction in consumption. V

Moreover for a same length of stroke, the expansion is more considerable than in a normal motor by reason of the small height "which it is possible to give to the exhaust ports which receive moreover a very high total cross section,

which allows the obtention of very high running 4 speeds.

It should be noted-finally that these advantages are by no means obtained at the expense of the simplicity of the operation or by the introduction of devices or mechanisms which are costly to establish. The cost price of this motor is as a matter of fact substantially comparable with that of any conventional motor.

My improved motor may also be designed for injection feed. I j Lastly, as obvious an das apparent moreover from the above disclosure, my invention is by no means limited to the single form hereinabove nor to that of its difierentparts nor to their relative positioning as shown, it covers on the in execution thereof...

The manner of feeding the motor as described is notthe onlymanner suitable for said motor. Nothing prevents the combustion mixturefrorn being admitted both .through the admission means H) and 18, provided the ports 18 open inside a collecting pipe similar tothe pipe ll.

What I claim is:

1. A twostroke motor comprising a cylinder including two parts of different radii, a hollow stepped piston adapted to reciprocate in said cylinder, the narrower part of which forms a combustion chamber, a casing communicating with the inside of the piston and closing the base der when the piston has moved outwardly, means passing through the inner end of the outer wall of thepiston at a location angularly shifted witirsaid feeding means fortrans'ferring said part of the combustible mixture through the hollow piston from the compression chamber into the casing when the piston has returned inwardly and subsequently transferring the mixture through the piston from the casing into the larger part'of the cylinder when the piston has moved again outwardly and exhaust means communicating with the larger part of the cylinder.

2.,A two stroke motor comprising a cylinder including two parts of different radii, a hollow stepped piston adapted to reciprocate in said cylinder, the narrower part of which forms a combustion chamber, 3; casing communicating with the inside of the piston and closing the base of-the larger part of the cylinder, means for feeding a part of the combustible mixture into the outer end of the narrower part of thev cylinder when the piston has moved outwardly, meansfor admitting directly the remaining component of the mixture into the casing when the piston has returned inwardly, means passing through the inner end of the outer wallof the piston at a location angularly shifted with said feeding means for transferring said part of the combustible mixture through the hollow piston from the compression chamber into the casing when the piston has returned inwardly and sub: sequently transferring the two portions of the mixture together through the piston from the easing into the larger part of the cylinder when the piston has moved again outwardly and exhaust means communicating with the larger part of the cylinder.

3. A two stroke motor comprising a cylinderincluding two parts of different radii, a hollow stepped piston adapted to reciprocate in said cylinder, the narrower part of which forms'a combustion chamber, a casing communicating with the inside of the piston and closing the base of the larger part of the cylinder, unrestricted permanently open means for feeding a part of the combustible mixture into the outer end of the narrower part of the cylinderwhen the piston has moved outwardly, unrestricted permanently open means for admitting directly the remaining component of the mixture into the casing when the piston has returned .inwardly, unrestricted permanently open means passing through the inner end of the outer wall ofthe piston at a location angularly shifted with said feeding means for transferring said part of the combustible mixture through the hollow pistonfrom the compression chamber into the casing when the piston has returned inwardly and subsequently transferring the two portions of the mixture together through the piston from the casing into the larger part of the cylinder when the piston has moved again outwardly and exhaust means communicating with the larger part of the cylinder. 7

4. A two stroke motor comprising a cylinder including two parts of different radii, a hollow stepped piston adapted to reciprocate in said cylinder, the narrower part .of which forms a combustible chamber, a casing communicating with the inside of the piston and closing the base of the larger part of the cylinder, means for feeding a part of the combustible mixture into the narrower part of the cylinder when the piston has moved outwardly, means for admitting directly the remaining component remainder of the mixture into the casing when the piston has returned inwardly, means passing through the inner end of the outer wall of the piston for transferring said part of the combustible mixture through the hollow piston from the compression chamber into the casing when the piston has returned inwardly and subsequently transferring the two portions of the mixture together through the piston from the casing into the larger part of the cylinder when the piston has moved again outwardly and exhaust means communicating with the larger part of the cylinder.

5. A two stroke motor comprising a cylinder including two parts of diiferent radii, a hollow stepped piston adapted to reciprocate in said cylinder, a ring shaped compression chamber surrounding the inner end of the narrower part of the cylinder and communicating therewith, a casing communicating with the inside of the piston and closing the base of the larger part of the cylinder, means for feeding a part of the combustible mixture into the outer end of the narrower part of the cylinder when the piston has moved outwardly, means for admitting directly the remaining component of the mixture into the casing when the piston has returned inwardly, means passing through the inner end of the outer wall of the piston at a location angularly shifted with said feeding means for transferring said part of the combustible mixture through the hollow piston from the compression chamber into the casing when the piston has returned inwardly and subsequently transferring the two portions of the mixture together through the piston from the easing into the larger part of the cylinder when the piston has moved again outwardly and exhaust means communicating with the larger part of the cylinder.

6. A two stroke motor comprising a cylinder including two parts of different radii, a hollow stepped piston adapted to reciprocate in said cylinder, the narrower part of which forms a combustion chamber, a casing communicating with the inside of the piston and closing the base of the larger part of the cylinder, means for feeding a part of the combustible mixture into the outer end of the narrower part of the cylinder when the piston has moved outwardly, means for ad- Knitting directly the remainder of the mixture into the casing when the piston has returned inwardly, means passing through the inner end of the outer wall of the piston at a location'angularly shifted with said feeding means for transferring said part of the combustible mixture through the hollow piston from the compression I REFERENCES CITED Thefollowing references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 584,674 Dake June, 15, 1897 871,319 Bissell -Nov. 19, 1907 1,240,980 Juengst "Sept. 25, 1917 FOREIGN PATENTS Number Country 7 Date 352,650 France 1905 403,380 France 1909. 177,214 Great Britain 1922 

